With the Revolution of 1930 in Brazil, Mena Barreto and Augusto Tasso Fragoso orchestrated an uprising in the Federal District, overthrowing President Washington Luís and establishing the 1930 junta.

After the junta transferred power to revolutionaries, Mena Barreto became the federal interventor for Rio de Janeiro and a mediator in the Constitutionalist Revolution of 1932.

Since the 18th century, with the tradition having begun with João de Deus Barreto Pereira Pinto (1769–1849), Viscount of São Gabriel, many members of his family had pursued a military career; 15 of them achieved generalship.

In May, along with his colleagues, Mena Barreto joined the palace guard loyal to the state government of Francisco da Silva Tavares, trying to subdue a protest movement against the violent repression of a rally that commemorated the second anniversary of the abolition of slavery.

[1][2][3] In January 1893, after asking to be excluded from the student body at the military academy, Mena Barreto joined the 4th Infantry Battalion, headquartered in São Gabriel.

After their victory, Mena Barreto was commissioned as an ensign, and he joined the Military School of Rio de Janeiro, then the Federal District, in March 1898.

In September 1921, he was promoted to brigadier general, and two months later he was appointed inspector of infantry of the 1st and 2nd Military Regions, located in the Federal District and São Paulo, respectively.

The first of a series of tenente revolts, Mena Barreto personally headed a detachment with the purpose of halting the advance of Military School cadets in the Rio neighborhood of Méier.

With the situation across Brazil turning favorable to revolutionaries, and Colonel Bertoldo Klinger, Mena Barreto's Chief of Staff, having asked the general on the behalf of a group of young officers to intervene in the revolution to end hostilities, Mena Barreto, alongside other generals in the Federal District, began to support a military coup.

[1] Mena Barreto's sons, Lieutenants Valdemar and João de Deus, made contact with the officialdom as signatures were being collected for a manifesto to force Luís's resignation.

In order to respect the military hierarchy, Mena Barreto had requested two generals superior to him, Augusto Tasso Fragoso and Alexandre Henrique Vieira Leal, to lead the movement.

Meanwhile, a provisional governing junta composed of Tasso Fragoso as head, Mena Barreto, and Noronha was established in place of the deposed president.

During their brief time in power, the junta began to demilitarize Brazil, appointed a provisional ministry, and authorized banking operations to resume among other measures.